1. Field of the Invention
This invention relates to a radiation devices, and more specifically, to an apparatus which is coupled to a radiation device which will allow the radiation device to alter the amount of radiation delivered to the body.
2. Description of the Prior Art
Cancer is the second leading cause of death in the U.S., exceeded only by heart disease. The American Cancer Society predicts that over 1.2 million new cancer cases would be diagnosed in the U.S. this year and that over 550,000 Americans would die of the disease. At this rate, approximately 1,500 Americans die each day of cancer.
In order to treat patients diagnosed with cancer, doctors generally have three alternatives: surgery, chemotherapy, and radiation therapy. These techniques are often used in combination with one another. Radiation therapy is generally used in treatment of nearly two-thirds of all cancer patients. In radiation therapy, high-energy rays are used to damage cancer cells and stop the cancer cells from growing and dividing. Thus, radiation therapy may stop the growth of a cancerous tumor and even destroy all the cells of the tumor. Where complete tumor destruction is not possible, radiation may be used to shrink a tumor, so that it can be more easily removed surgically. Radiation may also be used after surgery to destroy microscopic remnants of the cancer which were not removed during surgery.
Radiation therapy is generally used as a local treatment. In other words, radiation treatment is suppose to affect cancer cells only in the treated area. This is in contrast to chemotherapy. Chemotherapy kills cancer cells throughout the body and kills many healthy cells as well. While the goal of radiation therapy is to deliver radiation only to the treatment area, various limitations exists. For example, in treating prostrate cancer with external radiation therapy, the radiation beam may pass through portions of the skin, rectum, bladder, and genitalia, often causing inflamation and potentially serious damage to those tissues and organs.
To minimize these negative effects, it is important to deliver as much radiation to a target area as possible, while minimizing the amount of radiation delivered to surrounding healthy structures. Advances in radiation therapy techniques aid in this regard. One such technique is called xe2x80x9cintensity modulated radiation therapyxe2x80x9d (xe2x80x9cIMRTxe2x80x9d). As with most radiation therapy techniques, IMRT involves two stagesxe2x80x94treatment planning and radiation delivery. Treatment planning involves examining the area of cancer in a patient via imaging studies, such as computed tomography studies (xe2x80x9cCT scansxe2x80x9d) and/or magnetic resonance imaging (xe2x80x9cMRIxe2x80x9d). Typically, a clinician responsible for treatment planning, such as a radiation oncologist, then defines the optimal dose of radiation to be delivered to the treatment site and the tolerable level of radiation to be administered to the surrounding tissues. Sophisticated computer software processes the imaging information and clinician defined parameters to create a treatment plan. Another set of sophisticated software then translates the treatment plan into instructions for a radiation delivery device. A radiation delivery device used for IMRT typically includes a radiation accelerator, which creates a beam of radiation, and a radiation beam collimator (or multi-leaf collimator xe2x80x9cMLCxe2x80x9d), which blocks portions of the beam for specific time intervals. Both the accelerator and the MLC are typically controlled by instructions formulated by the computer software mentioned above.
The objective of IMRT is to partially block portions of a radiation beam that pass through important healthy bodily structures, to reduce radiation doses to those structures, while allowing as much of the radiation beam as possible to arrive at a cancerous target area. Treatment results have shown that this objective is being met. For example, IMRT has been used successfully over the past several years to treat prostate cancer while decreasing doses to the rectum and bladder, at such hospitals as Memorial Sloan Ketering Cancer Center.
While IMRT techniques provide a potentially revolutionary approach to radiation therapy, the vast majority of the clinics, hospitals, and other facilities that provide radiation therapy cannot afford the equipment to provide it. As healthcare cost increase throughout the world, healthcare providers must make difficult choices regarding how to provide the best possible services at prices their patients can afford. Although most clinicians would prefer to purchase every cutting edge medical technology available, they simply cannot afford to do so while still caring for their patients in an affordable manner.
The basic machinery needed to provide IMRT is a linear accelerator, an MLC, a computer system for controlling the accelerator and the MLC, and a computer system for creating treatment plans. Unfortunately, only about 10% of the currently used radiation therapy systems can be upgraded with these components to provide IMRT. Most currently used systems are typically incompatible because linear accelerators must be digital to be upgraded to provide IMRT, and most currently available systems use analog accelerators.
Unfortunately, most healthcare providers cannot afford a new IMRT radiation therapy system. Furthermore, it generally fairly expensive to upgrade to a digital radiation therapy system to provide IMRT.
A cheaper alternative to IMRT is to use a radiation modulating device for wholly or partially blocking one or more portions of a radiation beam. In this alternative, a radiation modulating device is positioned between a radiation source and a target area. The radiation beam will be blocked in such a manner as to vary the intensities across its field when it reaches a target. Thus, a radiation modulating device may be configured to specifically vary the intensities of a radiation beam to have a given effect on a target and/or on areas surrounding a target. For example, a radiation modulating device may be configured to allow a sufficient intensity of a radiation beam to be delivered to one area of a cancerous tumor, while limiting the intensity of the beam being delivered to a vital structure surrounding the tumor.
One problem with radiation modulating devices is that in order to alter the intensity of a radiation beam to be delivered to different patients, different radiation modulating devices must be positioned between the radiation source and the target area. This requires the removal of the current radiation modulating device, and the placement of a new radiation modulating device between the radiation source and the target area. Furthermore, to treat different areas of person""s body, different radiation modulating devices must be positioned between the radiation source and the target area. This requires the stoppage of radiation treatment, the removal of the current radiation modulating device, and the placement of a new radiation modulating device between the radiation source and the target area.
Therefore, a need existed-to provide a device and method that enables conventional radiation therapy systems to be adapted to provide innovative therapy techniques in a cost effective, manner. The device and method must be able to over come the problems associated with prior art devices and methods.
In accordance with one embodiment of the present invention, it is an object of the present invention to provide a device and method that enables conventional radiation therapy systems to be adapted to provide innovative therapy techniques in a cost effective manner.
It is another object of the present invention to provide a device and method that enables conventional radiation therapy systems to be adapted to provide innovative therapy techniques in a cost effective manner that is able to over come the problems associated with prior art devices and methods.
In accordance with one embodiment of the present invention an apparatus for altering the radiation intensity delivered from a radiation source is disclosed. The apparatus comprises a plate member for holding a plurality of radiation modulating devices. A frame member is coupled to the radiation source for holding the plate member between the radiation source and a target area. The frame member allows the plate member to rotate within the frame member so different radiation modulating devices may be positioned between the radiation source and the target area to alter the radiation intensity delivered.